Recent developments in the fields of computer driven hydraulic and pneumatic equipment coupled with research needs in medical instrumentation has resulted in a requirement for an efficient electrically operated pinch valve which operates in conjunction with flexible tubing. This type of valve is needed in order to ensure that the fluid flowing in the tubing is not contaminated by contact with components of the control valve, as would be the case if conventional solenoid valves were utilized. This need is present in medical instrumentation in which it is extremely important to maintain the fluid or gas in a sterile and uncontaminated condition.
Another application of this type of valve is related to the pumping and control of corrosive liquids or gases. Such liquids or gases contribute toward the damage of conventional control valves, resulting in unwanted leakage and a need for costly and time consuming replacement of the control valve.
It is desirable that pinch type valves used with flexible tubing be capable of being installed on tubing which is already in place, without a need for securing and passing the end of the tubing through the valve. This makes it possible to install such pinch valves quickly and in the case of experimental equipment makes it possible to modify such equipment without a need for total disassembly.
Another need which exists in the field of hydraulic and pneumatic equipment is for simultaneous and reliable control of two or more fluids or gases which may not mix.